Honor saved WebUI off during unconfigured boot setup

An enabled MQTT bridge without a saved SSID forced WebConfig back on at boot,
even after set webui off. Its setup AP also suspended an enabled ESP-NOW bridge.

Use first-time MQTT setup as the default only when no WebUI choice is saved.
Apply the saved on/off setting afterward in Repeater and Room Server. Preserve
first-time provisioning and explicit starts.

Add executable boot regressions for both roles with unset, on and off WebUI
settings and configured/unconfigured WiFi. Update setup and picker guidance.

docs/_javascript/firmware_picker.js

@@ -2175,7 +2175,7 @@
         "Use get logging.output and set logging.output off|usb|wifi|both to choose the saved output mode. Avoid both when two consumers publish the same packets to one broker."
       );
       extra.push(
-        "With no saved SSID, the setup AP stays available for 30 minutes after each boot, then Wi-Fi powers off automatically until reboot or an explicit start webconfig command. A configured Wi-Fi mode keeps reconnecting instead."
+        "With no saved SSID, automatic setup offers a 30-minute AP window per boot. Use set webui off to disable automatic setup after reboot. An explicit start webconfig command can reopen it. A configured Wi-Fi mode keeps reconnecting instead."
       );
     } else if (profile.logging === "usb-runtime") {
       if (!isFullCompanion(profile)) {